Happy Numbers

Difficulty:
Medium

Tags:
arithmetic

Instructions:
Happy numbers are positive integers that follow a particular formula: take each individual digit,
square it, and then sum the squares to get a new number. Repeat with the new number and eventually,
you might get to a number whose squared sum is 1. This is a happy number. An unhappy number (or
sad number) is one that loops endlessly. Write a function that determines if a number is happy or not.

Hidden Code:
There is hidden code with assertions that is also being run to test out your code.